1. Field of the Invention
Implementations of various techniques described herein generally relate to data processing. More specifically, various techniques described herein generally relate to seismic data processing.
2. Description of the Related Art
The following descriptions and examples do not constitute an admission as prior art by virtue of their inclusion within this section.
In a typical seismic survey, a plurality of seismic sources, such as explosives, vibrators, airguns or the like, may be sequentially activated at or near the surface of the earth to generate energy which may propagate into and through the earth. The seismic waves may be reflected back by geological formations within the earth. The resultant seismic wave field may be sampled by a plurality of seismic sensors, such as geophones, hydrophones and the like. Each sensor may be configured to acquire seismic data at the sensor's location, normally in the form of a seismogram representing the value of some characteristic of the seismic wave field against time. The acquired seismograms or seismic data may be transmitted wirelessly or over electrical or optical cables to a recorder system. The recorder system may then store, analyze, and/or transmit the seismograms. This data may be used to detect the possible presence of hydrocarbons, changes in the subsurface and the like.
In some circumstances, sampled data (e.g., the seismic data described above) may be acquired at irregular locations. That is, data may be acquired from locations which were not planned to be sampled. For example, seismic data may be planned to be sampled in a first location. However, an obstacle (e.g., a building) may be located on top of the first location. Consequently, a sensor or receiver may not be placed at the planned first location. Therefore, the sensor may have to be placed in a second location which is close to the first location, but is not the same as the planned location. This second location may be referred to as an irregular location. Many receivers may acquire seismic data at irregular locations, resulting in irregularly spaced data.
After acquiring sampled data, the data may be processed using specific signal-processing algorithms. For example, Fourier transforms may be applied to the data. The signal-processing algorithms (e.g., Fourier transforms) may require the data to be located at regularly spaced locations. For example, the algorithms may require the data to be located at the nodes of a regularly spaced grid (e.g., a Polar coordinate system). If the data is not located at regularly spaced locations, the results of the signal-processing algorithms may be inaccurate or distorted. Consequently, using irregularly sampled data may result in inaccurate or distorted results.
One solution to the problem of having data at irregularly spaced locations while the data is needed at regularly spaced locations is to use the data at the irregularly spaced locations to estimate the data at regularly spaced locations. Obtaining data at regular locations from data which was measured at irregular locations is commonly referred to as re-sampling or interpolation. The process of interpolating data or re-sampling data onto a regular grid from data sampled at irregular locations is called regularization or gridding. Regularization of seismic data is often a very important pre-processing step for several data processing algorithms, including 3-dimensional SRME, migration and 4-dimensional survey matching.
Although the aforementioned interpolation techniques allowed for estimation of data from irregularly spaced samples, the accuracy of interpolated data from the aforementioned techniques may still be improved and the interpolated data may also suffer from the effects of noise.